PDF Name Triangles – NCERT Book Class 9th Maths Chapter 7 21 1.6 MB English PDF PREVIEW

## Introduction to Class 9th Maths Chapter 7

The Class 9th Maths Chapter 7 is about triangles. It starts with an introduction to triangles, their sides, angles, and vertices. The chapter then goes on to discuss the congruence of triangles, rules of congruence, and some more properties of triangles.

The chapter also covers inequalities in a triangle. Overall, Triangles class 9 PDF provides a detailed understanding of triangles and their properties.

## What will you learn from this chapter?

In this Class 9th Maths Chapter 7, you will learn about triangles and their properties. Specifically, you will learn about the introduction to triangles, their sides, angles, and vertices. The chapter also covers the congruence of triangles, rules of congruence, and some more properties of triangles.

Additionally, the chapter discusses inequalities in a triangle. By the end of the chapter, you will have a better understanding of triangles and their properties.

### What is a triangle and what are its properties?

A triangle is a three-sided polygon with three angles and three vertices. Its properties include the sum of its angles being 180 degrees, the length of its sides, and the relationship between its sides and angles.

### How can we prove the congruence of two triangles?

Two triangles are congruent if their corresponding sides and angles are equal. We can prove the congruence of two triangles using various rules such as SSS, SAS, ASA, and RHS.

### What are the rules of congruence for triangles?

The rules of congruence for triangles include SSS (side-side-side), SAS (side-angle-side), ASA (angle-side-angle), and RHS (right-angle-hypotenuse-side).

### What are some of the properties of triangles?

Some properties of triangles include the Pythagorean theorem, the sum of its angles being 180 degrees, the sides opposite to equal angles being equal, and the median of a triangle dividing it into two equal areas.

### What are the inequalities in a triangle?

The inequalities in a triangle include the triangle inequality theorem, which states that the sum of any two sides of a triangle must be greater than the third side.

### How can we use the properties of triangles to solve problems?

We can use the properties of triangles to solve problems related to their sides, angles, and areas. For example, we can use the Pythagorean theorem to find the length of a side of a right triangle.

### What are some real-life applications of triangles and their properties?

Triangles and their properties have many real-life applications, such as in architecture, engineering, and navigation.

### How can we classify triangles based on their sides and angles?

We can classify triangles based on their sides as equilateral, isosceles, or scalene, and based on their angles as acute, obtuse, or right.

### What is the Pythagorean theorem and how can we use it to solve problems?

The Pythagorean theorem states that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides. We can use it to find the length of a side of a right triangle.

### How can we use trigonometry to solve problems related to triangles?

Trigonometry is the study of the relationships between the sides and angles of triangles. We can use trigonometry to solve problems related to the sides and angles of triangles, such as finding the length of a side or the measure of an angle.